Staged burner

ABSTRACT

A burner including a body having an air inlet at a first end and an outlet at a second end. A gas supply tube is disposed in the body and includes an air swirler and a nozzle at an end thereof. A plurality of outer gas spuds are disposed radially outwardly of the burner outlet, the outer gas spuds including a tube and a spud tip having a first set of openings that are directed generally parallel to an axis of the tube of the outer gas spuds and a second set of openings that are directed at an angle of at least ten degrees to the axis of the tube.

FIELD

The present disclosure relates to a fuel staged burner for improving flame shape and reducing emissions.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

Burner designs are commonly used for introducing fuel into a combustion chamber such as a furnace. Recently, the reduction of carbon monoxide and NO_(x) emissions have become common factors in the design of burners.

The present application is directed to a burner design for enhanced flame shape and reduced emissions.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

A burner including a body having an air inlet at a first end and an outlet at a second end. A gas supply tube is disposed in the body and includes an air swirler and a nozzle at an end thereof. A plurality of outer gas spuds are disposed radially outwardly of the burner outlet, the outer gas spuds including a tube and a spud tip having a first set of openings that are directed generally parallel to an axis of the tube of the outer gas spuds and a second set of openings that are directed at an angle of at least ten degrees to the axis of the tube.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a cross-sectional view of the stage burner according to the principles of the present disclosure; and

FIG. 2 is an end plan view of the stage burner shown in FIG. 1.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

With reference to FIGS. 1 and 2, the stage burner 10 according to the principles of the present disclosure will now be described. The stage burner 10 includes a gas fuel source 12 and a gas supply tube 14 with an air swirler 16 and a nozzle 18 at an end thereof. The gas supply tube extends through a venturi-shaped body 20 having an air inlet 22 at a first end and an outlet 24 that opens into a combustion chamber 26. The nozzle 18 is provided in a center of the venturi-shaped body 20 and terminates short of the outlet 24. The air swirler 16 surrounds the nozzle 18 near the outlet end of the nozzle.

A plurality of outer gas spuds 27 are disposed radially outwardly of the venturi-shaped body 20 and the outlet 24 and extend into the combustion chamber 26 through openings 28 through a wall 30 of the combustion chamber 26. Although four gas spuds 27 are shown in FIG. 2, it should be understood that as few as three and as many as eight gas spuds 27 can be utilized. Each of the outer gas spuds 27 have a tube 31 and a spud tip 32 that is provided with a plurality of openings 34A, 34B. A first set of the opening 34A are directed generally parallel to an axis of the tube 31 of the outer gas spuds 27. A second set of the openings 34B of the spud tips 32 open in a direction that is angled at an angle β to the axis of the outer gas spuds that is angled relative to a center axis of the outer gas spuds 27. Although other angles can be used, the angle β as shown in FIG. 1 is between 10 and 30 degrees and more particularly 20 degrees. In addition, the spud tips 32 are further oriented at an angle θ so that the second set of openings 34B are directed to inject fuel in a tangent fashion to the primary swirling airflow as shown in FIG. 2. Although other angles can be utilized, the angle θ as shown in FIG. 2 is between 30 and 60 degrees and more particularly 45 degrees.

As shown in FIG. 1, the pipes of the outer gas spuds 27 can be angled inward at an angle a that can be angled relative to an axis that is parallel to a center axis X of the venturi shaped body 20.The openings 28 through the wall 30 can be elongated so that the position of the outer gas spuds can be adjusted along the desired angle a as shown in FIG. 1. The center axis of the outer gas spuds 27 can be directed toward the angle a so that the gas injection direction is into the air flow exiting the venturi-shaped body 20 as shown in FIG. 1 Although other angles can be used depending upon the configuration of the burner chamber and other factors, the angle a illustrated in FIG. 1 is 2°.

The narrowing air inlet side of the venturi-shaped body 20 is designed to quickly and uniformly accelerate the air stream and then the expanding outlet side of the venturi-shaped body 20 is designed to gradually slow down the air stream for uniform mixing with the fuel. The fuel is staged to achieve lower NOx emissions (lower than so called ‘conventional’ burners which tend to mix the air and fuel in one step very quickly). The fuel staging is accomplished by injecting from 10-40% of the total gas through the center gas gun/nozzle 18 for stability purposes. This first stage of fuel gas mixes with the air immediately downstream of the air swirler 16 to achieve a stable flame. The swirler 16 is designed to swirl the air stream very hard which then creates a recirculation zone in front of the swirler 16 to achieve a stable flame.

Then the balance of the gas (60-90% by volume) is staged via the outer gas spuds 27 directly into the combustion chamber 26. The outer gas spuds 27 are designed with very high exit gas velocity in order to entrain large amounts of products of combustion to create a so called ‘internal flue gas recirculation’ in the furnace which helps to suppress the flame temperature and subsequently NOx generation.

The effect of the 2 sets of holes 34A, 34B in the spud tips is to create a faster mixing inner core of flame which then reacts more quickly to catch the outermost spud tip fuel resulting in an overall shorter and narrower flame than is otherwise possible with using axial only spud injectors. The effect of angling the injectors radially inboard also drives the mixing slightly faster for optimum flame shape. The design of the staged fuel injectors can be varied depending upon a particular application to provide the ability to match the staged fuel to mix with the air as desired for the available combustion volume/space which will change depending on the type of boiler so as to provide optimum emissions performance.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

1. A burner, comprising: a body having an air inlet at a first end and an outlet at a second end; a gas supply tube disposed in the body and including an air swirler and a nozzle at an end thereof; and a plurality of outer gas spuds each including a tube and a spud tip having a first set of openings that are directed generally parallel to an axis of the tube of the outer gas spuds and a second set of openings that are directed at an angle of at least ten degrees to the axis of the tube.
 2. The burner according to claim 1, wherein the spud tips of the plurality of outer gas spuds are oriented to inject fuel in a tangent fashion to a swirling airflow exiting the outlet of the body.
 3. The burner according to claim 2, wherein the tube of the plurality of outer gas spuds are angled relative to a center axis of the body.
 4. The burner according to claim 1, wherein the tube of the plurality of outer gas spuds are angled relative to a center axis of the body.
 5. The burner according to claim 1, wherein each of the tubes of the plurality of outer gas spuds are received in elongated openings in a wall defining a combustion chamber.
 6. A burner, comprising: a venturi-shaped body having an air inlet at a first end and an outlet at a second end; a gas supply tube disposed along a center axis of the venturi-shaped body and including an air swirler and a nozzle at an end thereof; and a plurality of outer gas spuds disposed radially outwardly of the burner outlet, the outer gas spuds including a tube and a spud tip having a first set of openings that are directed generally parallel to an axis of the tube of the outer gas spuds and a second set of openings that are directed at an angle of at least ten degrees to the axis of the tube.
 7. The burner according to claim 6, wherein the spud tips of the plurality of outer gas spuds are oriented to inject fuel in a tangent fashion to a swirling airflow exiting the outlet of the body.
 8. The burner according to claim 7, wherein the tube of the plurality of outer gas spuds are angled relative to a center axis of the body.
 9. The burner according to claim 6, wherein the tube of the plurality of outer gas spuds are angled relative to a center axis of the body.
 10. A burner, comprising: a venturi-shaped body having an air inlet at a first end and an outlet at a second end; a gas supply tube disposed along a center axis of the venturi-shaped body and including an air swirler and a nozzle at an end thereof; and a plurality of outer gas spuds disposed radially outwardly of the burner outlet, the outer gas spuds including a tube and a spud tip having a first set of openings that are directed generally parallel to an axis of the tube of the outer gas spuds and a second set of openings that are directed at an angle of at least ten degrees to the axis of the tube, wherein the tube of the plurality of outer gas spuds are angled relative to a center axis of the body. 